CN116510502A - Cement kiln flue gas denitration method - Google Patents
Cement kiln flue gas denitration method Download PDFInfo
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- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 49
- 239000003546 flue gas Substances 0.000 title claims abstract description 49
- 239000004568 cement Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 32
- 238000000197 pyrolysis Methods 0.000 claims abstract description 57
- 239000002699 waste material Substances 0.000 claims abstract description 31
- 239000007789 gas Substances 0.000 claims abstract description 28
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000007233 catalytic pyrolysis Methods 0.000 claims abstract description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 28
- 239000003054 catalyst Substances 0.000 claims description 17
- 229910052757 nitrogen Inorganic materials 0.000 claims description 14
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 8
- 244000261422 Lysimachia clethroides Species 0.000 claims description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 8
- 239000003513 alkali Substances 0.000 claims description 8
- 239000000460 chlorine Substances 0.000 claims description 8
- 229910052801 chlorine Inorganic materials 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052717 sulfur Inorganic materials 0.000 claims description 8
- 239000011593 sulfur Substances 0.000 claims description 8
- 239000010985 leather Substances 0.000 claims description 6
- 239000002808 molecular sieve Substances 0.000 claims description 6
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 229930195733 hydrocarbon Natural products 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 150000002430 hydrocarbons Chemical class 0.000 claims description 3
- 229910052723 transition metal Inorganic materials 0.000 claims description 3
- 150000003624 transition metals Chemical class 0.000 claims description 3
- 239000004519 grease Substances 0.000 claims description 2
- -1 hydrocarbon oxygen compounds Chemical class 0.000 claims description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 16
- 239000003638 chemical reducing agent Substances 0.000 abstract description 13
- 229910021529 ammonia Inorganic materials 0.000 abstract description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 abstract description 7
- 235000011114 ammonium hydroxide Nutrition 0.000 abstract description 7
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 abstract description 3
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000004202 carbamide Substances 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 238000002360 preparation method Methods 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 6
- 230000009467 reduction Effects 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000010531 catalytic reduction reaction Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 231100000252 nontoxic Toxicity 0.000 description 2
- 230000003000 nontoxic effect Effects 0.000 description 2
- 239000010920 waste tyre Substances 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003610 charcoal Substances 0.000 description 1
- 238000011278 co-treatment Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000004227 thermal cracking Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/208—Hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/21—Organic compounds not provided for in groups B01D2251/206 or B01D2251/208
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention discloses a cement kiln flue gas denitration method, which comprises the following steps: 1) Adding the nitrogenous waste into a pyrolysis furnace for directional catalytic pyrolysis to obtain pyrolysis gas and pyrolysis residues; 2) Introducing pyrolysis gas into the upper part of a decomposing furnace in a cement kiln system to perform flue gas denitration; 3) And (3) introducing pyrolysis residues into the lower part of a decomposing furnace in the cement kiln system to burn and release heat. According to the invention, the nitrogen-containing waste directional pyrolysis product is used for replacing reducing agents such as ammonia water, urea and the like to perform cement kiln flue gas denitration, so that not only is the preparation energy consumption of the reducing agents saved, but also secondary pollution such as ammonia escape and the like caused by SCR or SNCR is effectively avoided, and the method has remarkable environmental and economic benefits.
Description
Technical Field
The invention relates to the technical field of flue gas denitration, in particular to a cement kiln flue gas denitration method.
Background
The nitrogen oxides generated by the novel dry-method cement kiln system mainly comprise: 1) Thermal NO x (60% -70%) from the full combustion of head coal (about 40%) fed into the rotary kiln via kiln head; 2) Fuel type NO x And fast NO x (about 30% -40%) from tailing (about 60% of coal remaining) in the decomposing furnaceAnd (3) burning. NO-containing produced in rotary kilns in general x The flue gas enters the bottom of the decomposing furnace from the kiln tail, sequentially passes through cyclone preheaters of all stages from bottom to top, is then led to a raw material mill, and finally is discharged to the atmosphere by a tail-end flue gas treatment device.
The existing cement kiln flue gas denitration technology mainly comprises staged combustion, selective non-catalytic reduction (SNCR) and Selective Catalytic Reduction (SCR), and essentially uses C, CO and NH 3 Equal reducing agent and NO in flue gas x The reaction generates nontoxic and pollution-free N 2 And H 2 O. Selective non-catalytic reduction denitration technology widely applied in cement industry usually uses ammonia water as a reducing agent and reduces component NH by single effective reduction 3 With NO x The denitration efficiency of 50% -70% is finally realized by the reaction, the technology has the advantages of mature development, low construction cost, good technology expandability, small modification engineering quantity and the like, but the utilization rate of ammonia water is only 50% -60%, the ammonia emission is easy to exceed the standard, and the running cost is also higher. In addition, due to NH 3 Reduction of NO x The effective action area of the catalyst in the decomposing furnace is small, so that the denitration efficiency is low and the catalyst is greatly influenced by temperature.
To further improve NH 3 Denitration efficiency of SNCR technique, the methods often adopted include: 1) The ammonia injection point or the injection mode with better effect is selected, the method has low modification cost, but the improvement effect is very limited; 2) Introducing a suitable catalyst (NH 3 SCR), the method can realize high denitration efficiency>90 percent of the catalyst, but has the problems of short service life, high system power consumption, high investment and operation cost and the like; 3) The introduction of non-ammonia based reducing agents (e.g.: natural gas, synthesis gas, liquefied petroleum gas, etc.), the denitration effect of the method is good, but the operation cost is high as well.
Research shows that a small amount of ammonia (NH) is generated when nitrogen-containing waste such as sludge is cooperatively treated in a cement kiln x ) Hydrocarbons (C) x H y ) Alcohols (R-OH) and biomass charcoal, all of which can be used for reduction of NO x Alcohols can also widen NH 3 With NO x The temperature window of the reaction. However, conventional water is widely used in actual industrial productionThe technology of the mud kiln CO-treatment of the waste can only generate a small amount of reducing components such as CO and the like, and most of the waste is directly combusted to generate H without denitration activity 2 O and CO 2 The actual flue gas denitration effect is poor.
Therefore, the development of the directional catalytic pyrolysis denitration method for the nitrogenous wastes, which is applicable to the cement kiln system, has very important significance.
Disclosure of Invention
The invention aims to provide a cement kiln flue gas denitration method.
The technical scheme adopted by the invention is as follows:
a cement kiln flue gas denitration method, which comprises the following steps:
1) Adding the nitrogenous waste into a pyrolysis furnace for directional catalytic pyrolysis to obtain pyrolysis gas and pyrolysis residues;
2) Introducing pyrolysis gas into the upper part of a decomposing furnace in a cement kiln system to perform flue gas denitration;
3) And (3) introducing pyrolysis residues into the lower part of a decomposing furnace in the cement kiln system to burn and release heat.
Preferably, the nitrogenous waste in the step 1) is at least one of nitrogenous waste leather, nitrogenous junked tires and nitrogenous restaurant grease.
Preferably, the nitrogen content of the nitrogenous waste in the step 1) is more than or equal to 5.0%, the chlorine content is less than or equal to 1.0%, the alkali content is less than or equal to 1.5% and the sulfur content is less than or equal to 1.8%.
Preferably, the pyrolysis furnace in the step 1) is one of a fixed bed pyrolysis furnace, a fluidized bed pyrolysis furnace and a rotating bed pyrolysis furnace.
Preferably, the catalyst of the directional catalytic pyrolysis in the step 1) is a transition metal molecular sieve catalyst.
Further preferably, the catalyst of the directional catalytic pyrolysis in the step 1) is at least one of a Cu-SAPO-34 molecular sieve catalyst (Nanka university catalyst plant) and an Al-SBA-15 molecular sieve catalyst (Nanka university catalyst plant).
Preferably, the dosage of the transition metal molecular sieve catalyst is 1 to 5 times of the mass of the nitrogenous waste.
Preferably, the directional catalytic pyrolysis in the step 1) is carried out at 600-900 ℃, and the time of the directional catalytic pyrolysis is 5-20 s.
Preferably, the directional catalytic pyrolysis in the step 1) is performed in an atmosphere with the volume percentage of oxygen of 0.2% -3.0%.
Preferably, the main reducing component in the pyrolysis gas of step 2) is NH x 、HCN、H 2 、CO、C 1 ～C 8 Hydrocarbon, C of (2) 1 ～C 8 At least two of hydrocarbon oxygen compounds of (a) are provided.
Preferably, the residence time of the pyrolysis gas in the decomposing furnace in step 2) is greater than 2s.
Preferably, the spraying direction, angle and pressure of the pyrolysis gas in the step 2) are adjustable.
Preferably, the upper part of the decomposing furnace in the step 2) is a gooseneck to C 5 The area between the cyclones.
Preferably, in the step 2), the temperature of the upper part of the decomposing furnace is 800-900 ℃ and the air excess coefficient is 0.85-1.00.
Preferably, in the step 3), the lower part of the decomposing furnace is a region close to the tertiary air pipe.
In the invention, the common C (reaction formula 1), CO (reaction formulas 2 and 3) and NH are removed 3 Reducing agents such as (reaction formulas 4 and 5) can be used for denitration and CH generated by directional catalytic pyrolysis of nitrogenous wastes 4 (reaction 6 and 7), C 3 H 6 The reducing agent such as (equation 8) and HCN (equation 9) can also be mixed with NO x The reaction generates nontoxic and pollution-free N 2 、H 2 O and CO 2 The invention can show higher reactivity and denitration efficiency, and in addition, the invention can effectively reduce NH in the thermal pyrolysis gas of the nitrogen-containing waste 3 (equations 10 and 11) isothermal sensitive components, and CO (equation 12), CH 4 (reaction 13), C 3 H 6 (reaction formula 14) and other atmosphere sensitive components undergo side reactions without denitration activity, and the specific reaction formula is as follows:
2NO+C→N 2 +CO 2 (1)
2NO+2CO→N 2 +2CO 2 (2)
2NO 2 +4CO→N 2 +4CO 2 (3)
6NO+4NH 3 →5N 2 +6H 2 O (4)
6NO 2 +8NH 3 →7N 2 +12H 2 O (5)
4NO+CH 4 →2N 2 +2H 2 O+CO 2 (6)
4NO 2 +CH 4 →4NO+CO 2 +2H 2 O (7)
18NO+2C 3 H 6 →9N 2 +6H 2 O+6CO 2 (8)
10NO+4HCN→7N 2 +2H 2 O+4CO 2 (9)
2NH 3 →N 2 +3H 2 (10)
4NH 3 +5O 2 →4NO+6H 2 O (11)
2CO+O 2 →2CO 2 (12)
CH 4 +2O 2 →2H 2 O+CO 2 (13)
2C 3 H 6 +9O 2 →6H 2 O+6CO 2 (14)。
the beneficial effects of the invention are as follows: according to the invention, the nitrogen-containing waste directional pyrolysis product is used for replacing reducing agents such as ammonia water, urea and the like to perform cement kiln flue gas denitration, so that not only is the preparation energy consumption of the reducing agents saved, but also secondary pollution such as ammonia escape and the like caused by SCR or SNCR is effectively avoided, and the method has remarkable environmental and economic benefits.
Specifically:
1) The book is provided withThe invention can control the catalytic pyrolysis kinetics of the nitrogenous waste by controlling the temperature, atmosphere, time and catalyst types of pyrolysis, and can obtain the catalyst rich in NH x 、C x H y The reducing pyrolysis mixed gas of the components such as HCN, CO and the like can greatly improve the denitration efficiency (the waste is cooperatively treated by the traditional cement kiln to mainly generate a small amount of reducing component CO, and most of the waste is directly combusted to generate H without denitration activity) 2 O and CO 2 The flue gas denitration effect is poor);
2) The invention fully utilizes the C with high denitration activity x Reducing agents such as Hy, HCN and the like are reasonably matched with a cement kiln to cooperatively treat reduction products (R-OH and NH) generated by thermal cracking of nitrogenous wastes 3 Collocation can effectively enlarge NH 3 Denitration temperature window), and selecting the addition position in combination with the atmosphere and temperature distribution characteristics of the decomposing furnace, fully utilizing the denitration activity and combustion heat value of each pyrolysis product, and finally, obviously improving the denitration effect of each reduction component in the decomposing furnace (the denitration efficiency is improved by the traditional means usually through process adjustment, namely, the cement kiln environment is regulated and controlled to match with the NO reduced by the reducing agent x Conditions, which have a greater impact on the normal production of the cement kiln);
3) The invention can realize the NO in the flue gas of the cement kiln under the condition of NO need of additionally introducing reducing agents such as ammonia water, urea and the like x The source reduces the emission, and can also avoid secondary pollution caused by ammonia escape.
Detailed Description
The invention is further illustrated and described below in connection with specific examples.
Example 1:
a cement kiln flue gas denitration method, which comprises the following steps:
1) Uniformly mixing the waste tire containing nitrogen (14.8% by mass of nitrogen, 0.8% by mass of chlorine, 0.8% by mass of alkali and 1.4% by mass of sulfur) with the Cu-SAPO-34 molecular sieve catalyst according to the mass ratio of 0.4:1, adding the mixture into a fluidized bed pyrolysis furnace, and controlling the oxygen volume percentage in the fluidized bed pyrolysis furnace to be 2.0%, and pyrolyzing the mixture at 650-750 ℃ for 13s to obtain the catalystPyrolysis gas (the main reducing component being NH 3 、HCN、CH 4 、C 3 H 6 And C 2 H 5 OH) and pyrolysis residues;
2) Introducing pyrolysis gas into upper part of decomposing furnace (gooseneck to C) 5 The area between the cyclones) is subjected to flue gas denitration, the temperature of the area is 850-900 ℃, the air excess coefficient is 0.90-0.98, and the residence time of pyrolysis gas in a decomposing furnace is more than 2s;
3) And introducing pyrolysis residues into the lower part (a region close to the tertiary air pipe) of a decomposing furnace in the cement kiln system to burn and release heat.
The final flue gas denitration efficiency in this example was 90.18% by test.
Example 2:
a cement kiln flue gas denitration method, which comprises the following steps:
1) Uniformly mixing waste leather containing nitrogen (the mass percentage of nitrogen is 6.5%, the mass percentage of chlorine is 0.6%, the mass percentage of alkali is 1.2%, the mass percentage of sulfur is 1.6%) and Al-SBA-15 molecular sieve catalyst according to the mass ratio of 0.2:1, adding the mixture into a fixed bed pyrolysis furnace, controlling the volume percentage of oxygen in the fixed bed pyrolysis furnace to be 0.5%, and pyrolyzing the mixture at 800-850 ℃ for 6s to obtain pyrolysis gas (the main reducing component is NH) 3 、HCN、H 2 、CH 4 、C 2 H 4 And C 2 H 6 ) And pyrolysis residues;
2) Introducing pyrolysis gas into upper part of decomposing furnace (gooseneck to C) 5 The area between the cyclones) is subjected to flue gas denitration, the temperature of the area is 800-900 ℃, the air excess coefficient is 0.85-0.95, and the residence time of pyrolysis gas in a decomposing furnace is more than 2s;
3) And introducing pyrolysis residues into the lower part (a region close to the tertiary air pipe) of a decomposing furnace in the cement kiln system to burn and release heat.
The final flue gas denitration efficiency in this example was tested to be 88.72%.
Example 3:
a cement kiln flue gas denitration method, which comprises the following steps:
1) Uniformly mixing waste tires containing nitrogen (14.8% by mass of nitrogen, 0.8% by mass of chlorine, 0.8% by mass of alkali, 1.4% by mass of sulfur), waste leather containing nitrogen (6.5% by mass of nitrogen, 0.6% by mass of chlorine, 1.2% by mass of alkali, 1.6% by mass of sulfur) and Cu-SAPO-34 molecular sieve catalyst according to a mass ratio of 0.4:0.4:1, adding into a fluidized bed pyrolysis furnace, controlling the oxygen volume percentage in the fluidized bed pyrolysis furnace to be 2.0%, and pyrolyzing at 650-750 ℃ for 13s to obtain pyrolysis gas (the main reducing component is NH) 3 、HCN、H 2 、CH 4 、C 2 H 4 、C 3 H 6 And C 2 H 5 OH) and pyrolysis residues;
2) Introducing pyrolysis gas into upper part of decomposing furnace (gooseneck to C) 5 The area between the cyclones) is subjected to flue gas denitration, the temperature of the area is 850-900 ℃, the air excess coefficient is 0.90-0.98, and the residence time of pyrolysis gas in a decomposing furnace is more than 2s;
3) And introducing pyrolysis residues into the lower part (a region close to the tertiary air pipe) of a decomposing furnace in the cement kiln system to burn and release heat.
The final flue gas denitration efficiency in this example was tested to be 91.94%.
Comparative example 1:
a cement kiln flue gas denitration method, which comprises the following steps:
1) Adding waste leather containing nitrogen (the mass percentage of nitrogen is 6.5%, the mass percentage of chlorine is 0.6%, the mass percentage of alkali is 1.2%, and the mass percentage of sulfur is 1.6%) into a garbage incinerator for combustion to obtain decomposed gas;
2) Introducing the decomposing gas into the upper part (gooseneck to C) of the decomposing furnace in the cement kiln system 5 The area between the cyclones) is subjected to flue gas denitration, the temperature of the area is 800-900 ℃, the air excess coefficient is 0.85-0.95, and the residence time of pyrolysis gas in a decomposing furnace is more than 2s.
The final flue gas denitration efficiency in this comparative example was tested to be 42.79%.
Comparative example 2:
a cement kiln flue gas denitration method, which comprises the following steps:
the waste leather containing nitrogen (6.5% by weight of nitrogen, 0.6% by weight of chlorine, 1.2% by weight of alkali and 1.6% by weight of sulfur) is directly added to the upper part of a decomposing furnace (gooseneck to C) in a cement kiln system 5 The area between the cyclones) is subjected to flue gas denitration, the temperature of the area is 800-900 ℃, and the air excess coefficient is 0.85-0.95.
The final flue gas denitration efficiency in this comparative example was tested to be 40.12%.
Comparative example 3:
a cement kiln flue gas denitration method, which comprises the following steps:
introducing 12% ammonia water into the upper part of decomposing furnace (gooseneck to C) in cement kiln system via atomizing spray gun 5 The area between the cyclones) and the lower part (the area close to the tertiary air pipe) are used for flue gas denitration, wherein the temperature of the upper area of the decomposing furnace is 800-900 ℃, the air excess coefficient is 0.85-0.95, and the residence time of ammonia water in the decomposing furnace is more than 2s.
The final flue gas denitration efficiency in this comparative example was tested to be 58.26%.
It can be seen from the above that:
1) Examples 1 to 3 can increase the cement kiln flue gas denitration rate by 110% compared with the conventional technique of adding the nitrogen-containing waste to the garbage incinerator or directly to the decomposing furnace in comparative examples 1 and 2, which is mainly beneficial in that the directional catalytic pyrolysis of the nitrogen-containing waste can not only avoid the excessive oxidation of the nitrogen-containing waste, but also obtain the waste with stronger NO x NH of Selective reducing ability x And C x H y Pyrolysis gas is used for denitration;
2) Examples 1 to 3 compare with NH in comparative example 3 using ammonia as the single reducing agent 3 SNCR technology can increase the denitration rate of cement kiln flue gas by 60%, which is mainly beneficial toOriented catalytic pyrolysis of nitrogen-containing waste produces specific NH 3 C with higher denitration activity x H y And alcohol (R-OH) in the pyrolysis gas can expand NH 3 Reduction of NO x Is provided for the temperature window of (a).
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (10)
1. The cement kiln flue gas denitration method is characterized by comprising the following steps of:
1) Adding the nitrogenous waste into a pyrolysis furnace for directional catalytic pyrolysis to obtain pyrolysis gas and pyrolysis residues;
2) Introducing pyrolysis gas into the upper part of a decomposing furnace in a cement kiln system to perform flue gas denitration;
3) And (3) introducing pyrolysis residues into the lower part of a decomposing furnace in the cement kiln system to burn and release heat.
2. The cement kiln flue gas denitration method according to claim 1, wherein: the nitrogenous waste in the step 1) is at least one of nitrogenous waste leather, nitrogenous junked tires and nitrogenous restaurant grease.
3. The cement kiln flue gas denitration method according to claim 2, characterized in that: the nitrogen content of the nitrogenous waste in the step 1) is more than or equal to 5.0%, the chlorine content is less than or equal to 1.0%, the alkali content is less than or equal to 1.5%, and the sulfur content is less than or equal to 1.8%.
4. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: the pyrolysis furnace in the step 1) is one of a fixed bed pyrolysis furnace, a fluidized bed pyrolysis furnace and a rotating bed pyrolysis furnace.
5. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: the catalyst of the directional catalytic pyrolysis in the step 1) is a transition metal molecular sieve catalyst.
6. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: the directional catalytic pyrolysis in the step 1) is carried out at 600-900 ℃ for 5-20 s.
7. The cement kiln flue gas denitration method according to claim 6, wherein: the directional catalytic pyrolysis in the step 1) is carried out in an atmosphere with the volume percentage of oxygen of 0.2-3.0%.
8. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: step 2) the main reducing component in the pyrolysis gas is NH x 、HCN、H 2 、CO、C 1 ～C 8 Hydrocarbon, C of (2) 1 ～C 8 At least two of hydrocarbon oxygen compounds of (a) are provided.
9. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: the residence time of the pyrolysis gas in the decomposing furnace in the step 2) is more than 2s.
10. A cement kiln flue gas denitrification method according to any one of claims 1 to 3, wherein: step 2) the upper part of the decomposing furnace is a gooseneck to C 5 The area between the cyclones; and 3) the lower part of the decomposing furnace is a region close to the tertiary air pipe.
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